Sensitive and renewable picloram immunosensor based on paramagnetic immobilisation

• Published in: International journal of environmental analytical chemistry 2012-05, Vol.92 (6), p.729-741
• Main Authors: Zeng, Guang-Ming, Zhang, Yi, Tang, Lin, Chen, Li-Juan, Pang, Ya, Feng, Chong-Ling, Huang, Guo-He, Niu, Cheng-Gang
• Format: Article
• Language: English
• Subjects: barley; broadleaf weeds; carbon; chlorination; compost extracts; correlation; detection limit; electrochemistry; Electrodes; Freshwater; Hordeum vulgare; Immunoassay; immunoassays; immunosensor; immunosensors; laccase; magnetic nanoparticles; Nanoparticles; Pesticides; picloram; Plant growth; plant growth substances; regeneration; river water; storage quality; Triticum aestivum; wheat; woody plants
• ISSN: 1029-0397; 0306-7319; 1029-0397
• DOI: 10.1080/03067319.2010.496047

Picloram (4-amino-3,5,6-trichloro-2-pyridincarboxylic acid) is one of the chlorinated pesticides. It is widely used for control of wood plants, wheat, barley and wide range of broadleaf weeds as a plant growth regulator. An immunosensor was developed for detection of picloram concentration in compost extracts and river water. The laccase-picloram was prepared. The magnetic core-shell (Fe₃O₄-SiO₂) nanoparticles were modified with anti-picloram-IgG and attached to the surface of carbon paste electrode (CPE) with the aid of paramagnetism. Following competitive immunoreaction with picloram and the picloram-laccase to form immunocomplex, electrochemical measurement was carried out. After immunoassay, the electrode was immersed in glycin-hydrochloric acid buffer or polished with diamond paper for regeneration. The linear range for picloram detection was 1 × 10–⁴–10 µg mL–¹ with the correlation coefficient of 0.9936, and the detection limit is 1 × 10–⁴ µg mL–¹. The laccase labelled on the picloram for competitive immunoassay showed good activity, and the current response was strong and stable in electrochemical detection. The current reached 95% of the steady-state current within about 100 s. The proposed immunosensor exhibited good precision, sensitivity, selectivity, reusability, and storage stability.